In alt.os.linux.debian, MunderscoreNEWS@chareDOTorg.uk uttered the immortal
words:

>> An alternative is to edit the modes lines in the screen section of your
>> XF86Config-4 file:
>
> I did a search and could not find this file.

I didn't have a Debian box with X installed booted at the time. :-)

For reference and off the top of my head I think it's in /etc/X11. You might
have XF86Config instead of XF86Config-4.

--
Andy.